I have a wooden plank (like a flat swing seat) and a hanging chain (or two, like a swing). Instead of screwing an eye into the plank I want the chain to continue downwards through a hole in the plank, so that its height on the chain can be adjusted and other things can hang farther down the chain. Is there hardware designed specifically for this purpose, or a good combination of common hardware to accomplish this?
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1What kind of loads are involved? What kind of chain? Some types of heavy chain have little clearance for a through bolt. The wood crushing onto whatever support is probably the weakest...um...link.– bcworkzCommented Jan 30, 2013 at 0:46
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@bcworkz type of chain is not entirely determined yet. loads will be some hundreds of pounds (dynamic). might be metal instead of wood.– SparrCommented Jan 30, 2013 at 5:00
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2 Answers
The naive approach is to just put a bolt through the chain, below the plank, at the appropriate height, possibly with some washers around the chain to sit between the plank and the side of the bolt.
My biggest worry with this approach is how the bolt will interact with the other hanging chain link that passes through the same chain link that the bolt passes through.
Sparr's answer is good except that I will add that you might want to consider putting legs on the bottom with a bolt and cotter pin between them. I found this picture online that is pretty close to what you will want to do.
The cotter pin can be easily removed to shorten/lengthen the chain. The bolt is smooth so there won't be friction there and allows for the chain to move back and forth between the two legs. The only pressure against the pin is horizontal and it should hold.
The pressure on the legs will be equal to the weight on the plank, so be sure to beef them up well if you intend this to hold a good deal of weight, like the weight of a person for instance.
answered Jan 29, 2013 at 20:26
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The same worry applies with a pin as with a bolt... how does the pin interact with the lower chain link? They will both want to sit in the "bottom" of the chain link the pin goes through, and will be applying significant crushing force to each other.– SparrCommented Jan 29, 2013 at 21:26
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@Sparr I think you misunderstand, the chain will not touch the pin. The bolt will go through one link in the chain. The hole there in the picture demonstrates roughly where the chain is coming from. Commented Jan 30, 2013 at 0:32
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I meant the bolt, not the cotter pin. How does the bolt interact with the chain link?– SparrCommented Jan 30, 2013 at 5:00
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@Sparr It interacts yes by the bottom of the chain link interacting with the bottom of the bolt with a full transfer of pressure from what is sitting on the plank. The chain and bolt will be made of steel, it will require tons of force to crush steel like that or to snap a link in the chain. Even with a smaller thickness chain, the, legs will be crushed long before the chain is crushed. This is why it is more important to focus on bulky legs that are securely fastened against vertical and horizontal movement. Commented Jan 30, 2013 at 12:07